A CCFL (Cold Cathode Fluorescent Lamp) inverter with switching frequency adapted to the resonant tank characteristics will produce a very high efficiency power conversion and provide reliable lamp striking and open lamp regulation. However, this design approach also produces wide variations of switching frequencies when the input voltage, lamp current, and LCD panels change. If the frequency variation range is too wide, there is potential for EMI interference between the LCD panel and the CCFL inverter.
While it is desirable to drive CCFLs with fixed frequencies, the resonant tank characteristics of the inverter can be greatly influenced by the panel assembly which makes it difficult to achieve reliable ignition and open lamp operation.